NYPD Sgt. Damaris Diaz — the daughter of state Sen. Ruben Diaz Sr. and sister of Bronx Borough President Ruben Diaz Jr. — was arrested yesterday for keying her boyfriend’s car after he told her he wanted out of their relationship, cops said.

Diaz, 43, a divorced mother who has served with the Police Department since 1993, had been dating a fellow cop, Edward Vasquez.

The couple met on the job at the 41st Precinct station house in Longwood, once infamously known as “Fort Apache, The Bronx.”

But when Vasquez told her he wanted to break up with her, Diaz allegedly went ballistic and began threatening him via text message — taunting him with her family’s political power in The Bronx and her senior rank at the Police Department.

“I will go to the 4-1 and bury your career,” Diaz texted Vasquez, referring to the precinct station where he works, according to cop sources.

“You better come back,” she wrote.

In the most ominous message, she allegedly texted, “If you don’t come back, I will kill you.”

But the texting fusillade apparently wasn’t enough retribution for the spurned lover.

At 11:30 p.m. on Friday, Diaz spotted her ex-boyfriend’s 2005 Honda Accord parked on Hone Avenue in The Bronx and scratched it up with her key, cops said.

Police charged her with criminal mischief and aggravated harassment.

“He was trying to break up with her, and she had a problem with that,” a source said.

The incident came a week after The Post revealed that Assemblywoman Naomi Rivera — daughter of Assemblyman José Rivera — had employed two boyfriends on her payroll and misused taxpayer funds.

Friends of the Diaz clan said they were shocked by the arrest yesterday.

“I can’t see Damaris doing this,” said a source close to the sergeant. “She’s such a sweet person. That’s not Damaris. It’s not in her character.”

Her brother could not be reached for comment.

“I’m sick in my house. I’m eating right now, and I can’t talk to you,” Ruben Diaz Sr. said when reached by phone at his home yesterday afternoon.

This isn’t the first black eye for the Diaz clan.

The head of two Bronx charities with ties to Diaz Sr. was charged earlier this month with pilfering more than $500,000 in taxpayer dollars.

Diaz Sr. has claimed state Attorney General Eric Schneiderman holds a personal grudge against him.

Diaz Sr. claims the indictment of one of his top aides, Clement Gardner, came as a total shock.